During vehicle travel on roads having a very low coefficient-of-friction (commonly denoted by μ or mu) conditions, where the mu value may be below 0.1, it is likely that prior art anti-skid vehicle control systems will be unable to provide sufficient assistance if the vehicle starts to skid. Thus, there is an increased risk of the vehicle departing from the road or desired lane of travel. Such low-mu conditions may occur when so-called glare ice or black ice has formed on the road surface.
One situation when this may occur is during downhill travel on a low-mu surface. Even if the brakes of the vehicle are fully applied, the vehicle will not decelerate as the low-mu surface will provide no or very limited traction. The friction between the road and vehicle tires may most likely be unable to hold the vehicle on the surface due to the road gradient.
Today's anti-skid control systems generally attempt to stabilize a vehicle which start to skid on the low-mu surface by applying individual brake actuations in order to increase longitudinal tire forces on the braked wheel/wheels. This will, however, be of limited use when the driver commands full braking.
Conventional vehicle controllers, e.g. so called Electronic Stability Controllers (ESC), attempt to assist a driver during turning by applying the brakes at one or more wheels of the vehicle. If the driver brakes hard and the conventional ESC intervenes to stabilize the vehicle, the vehicle may not turn since all wheels are braked to the point that all tire forces are saturated.
Thus, a brake intervention from a conventional anti-skid control system when travelling on a low-mu surface road may fail to bring the vehicle back to the originally travelled lane once the vehicle starts to skid.
During vehicle travel on roads having a very low coefficient-of-friction (commonly denoted by μ or mu) conditions, where the mu value may be below 0.1, it is likely that prior art anti-skid vehicle control systems will be unable to provide sufficient assistance if the vehicle starts to skid. Thus, there is an increased risk of the vehicle departing from the road or desired lane of travel. Such low-mu conditions may occur when so-called glare ice or black ice has formed on the road surface.
One situation when this may occur is during downhill travel on a low-mu surface. Even if the brakes of the vehicle are fully applied, the vehicle will not decelerate as the low-mu surface will provide no or very limited traction. The friction between the road and vehicle tires may most likely be unable to hold the vehicle on the surface due to the road gradient.
Today's anti-skid control systems generally attempt to stabilize a vehicle which start to skid on the low-mu surface by applying individual brake actuations in order to increase longitudinal tire forces on the braked wheel/wheels. This will, however, be of limited use when the driver commands full braking.
Conventional vehicle controllers, e.g. so called Electronic Stability Controllers (ESC), attempt to assist a driver during turning by applying the brakes at one or more wheels of the vehicle. If the driver brakes hard and the conventional ESC intervenes to stabilize the vehicle, the vehicle may not turn since all wheels are braked to the point that all tire forces are saturated.
Thus, a brake intervention from a conventional anti-skid control system when travelling on a low-mu surface road may fail to bring the vehicle back to the originally travelled lane once the vehicle starts to skid.